Background: Light is a known factor affecting mood and the circadian system. Light deficit is linked to deteriorated transduction of photic information to the brain, and reduced amplitude of the perceived circadian light signaling. Retinal ganglion cells (RGCs) loss due to advanced glaucoma can be a factor compromising light perception, with consequences for circadian rhythms, sleep and mood. This study aimed to estimate associations of RGCs loss with a depression score by multiple regression, accounting for other features of glaucoma.
Methods: One hundred and fifteen patients diagnosed with primary open-angle glaucoma completed the Beck Depression Inventory II questionnaire. The damage to their RGCs was assessed by high-definition optical coherence tomography (HD-OCT) and their function by pattern electroretinogram (PERG). On fifteen of these patients, 24-h salivary melatonin patterns were determined under light-controlled laboratory conditions, and analysis of eight clock related gene polymorphisms was performed.
Results: Backward stepwise multiple regression revealed that the BDI score was the strongest factor that was most closely associated with the HD-OCT-based percentage of global RGCs loss (standardized coefficient, b* = 0.784, p < 0.001), surpassing other related factors, including age, intraocular pressure, visual field loss, and PERG amplitude. A high BDI score was associated with the GNβ3 825C > T polymorphism (dbSNP rs5443).
Limitations: This study did not specifically address damage to intrinsically photoreceptive RGCs. The gene study is based on a limited number of volunteers.
Conclusions: Depression scores are strongly associated with RGCs loss, increasing abruptly above a threshold of 15 %, supporting the hypothesis that RGCs loss in advanced glaucoma may affect non-visual photic transduction and lead to mood disturbances.
Keywords: Beck depression inventory; Circadian disruption; GNβ3 rs5443; Glaucoma; Retinal ganglion cells; Sleep.
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